For what it's worth I see the below also as the potential sign of a nice correction. I have just started reading the books recommended above, and just read the section about narrowing triangle of a fifth wave (so I may be searching for the sign at the moment) and it meaning a potential harsh correction because of a too fast move in the way of the trend too quickly, so it's needing a nice correction. In my opinion btc did rise astronomically last year and such this type of correction may make sense after a year that seen btc rise more than 1800% last year for the year from around 800 to start the year to as high as 18k at the near end of the year. Take the chart for what you will:

It would be nice for someone that knows more than I to comment on the chart. @haejin